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Yamaha XS 1100 Forum

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zebedeus-bartolomeus Offline

Beiträge: 5

28.09.2009 16:55
my bike random does not start Thread geschlossen

Hello There,

I hope that someone can help me with the following problem. On an intermittent base my bike won't start. Extra problem with this is that when it starts it looks that the timing is to late.

I know that bad ignition timing is mainly the cause that de the FatBoy wouldnot start and the window for adjustments is very small.

But first of all, has one of you any idea what the cause can be of the intermittent failure of starting can be.

I checked already timing, (which looks to be late), ignition coils, pickup coils, wiring to the ignition box on the rearfender for broken/loose cable and/or connectors or dirty connectors. I have a good spark (5mm in open air) and nice light bleu.

Looking forward for some helpfull hints.

Yours sincerally

Hans van Leeuwen

xsTom Offline

Beiträge: 246

28.09.2009 21:32
#2 RE: my bike random does not start Thread geschlossen


First,my English is not so good.
What kind of Xs1100 is it?

The Timing from the Pick up Coils on the left Side from the Engine can be too early?

Has the Engine a duty Control -inlet manifold vacuum on the Carburator - with a pressure Sensor ? or mechanic adjustment on the Coilboard?
Is it OK?


AndyNL Offline

Beiträge: 268

28.09.2009 22:00
#3 RE: my bike random does not start Thread geschlossen

Hoi Hans schrijf me maar op dan zal ik je proberen te helpen.
Mvg Andreas

zebedeus-bartolomeus Offline

Beiträge: 5

07.10.2009 23:57
#4 RE: my bike random does not start Thread geschlossen

Thanks for the help from Andy so far. It seems that I had two problems.
One was ignition. When i was trying to solve my problem(s)by mistake i swapped two sparkplug cables. (I know quit stupid but sh... happens)

The other one is that the engine only pickups his revs when its already runing about 3000 rpms. In lower rpms (850/1000) the engine wouldnot pickup. It runs good in stationary situation ! I checked all the carbs for settings/cleaning/and correct parts and defectives.

When I look in to the air-inlet from the carbs (airfilter removed) the gasneedles starts "bouncing" when I open the gasthrottle from stationar rpms (± 900-1000 revs) when the engine has reached about 3000-3500 rpms and I open the throttle further the gasneedles goes smooth up and down.

What's wrong, or what is my wrong interpretation of what is happening???

Feel free to answer in German language, that's no problem for reading but a bit for writing for me.

Looking forward for your ideas.

Greetings Hans

Micha HH ( gelöscht )

08.10.2009 21:36
#5 RE: my bike random does not start Thread geschlossen

Hello Hans!

Question: which exhaustsystem is installed on your bike? A diffrent one off the original parts can cause problems when accelerating the engine till 3000-4000 rpm.

In case of partial load it is normal, that the needles starts to shake a little bit, but you dont feel this when driving. But, engine whith bad acceleration shoes realy trembling needles.

If you remove the airfilter this will cause a lean air fuel mixture.

Engine idle air fuel mixture is already checked whith colortune?
What`s happend whith the syncronization off the carburators?

Micha HH

Art Offline

Beiträge: 168

11.10.2009 20:56
#6 RE: my bike random does not start Thread geschlossen

Hello Hans,

have a look here.

There are some XS1100 carbs in action.

Meine Bikes:
XS 1100 EZ. 4/78;
FZR 1000 EZ. 3/89

zebedeus-bartolomeus Offline

Beiträge: 5

11.10.2009 23:48
#7 RE: my bike random does not start Thread geschlossen

Hello Micha,

Sorry that I respond so late but I have a job to .

To answer your questions:
It is a standard exhaust system with the bike has been in use for more then 8 years so that cannot be the problem.

The synchonisation of the carbs is OK. It could be adjusted with professional equipment all at once but i can only adjust them separatly. The difference will be less then 5% i am sure about that.

Allthough I am aware that removal off the airfilter leans the air-fule mixture that may be of no influence in running the engine without any load.

My problem happens (Just like sh.. happens) with no load. The engine runs at iddle rpms but does not pick up or with a lack of enthousiasme until it reaches 3000-3500 rpms. Then it finctions smoothly and response OK on the throttle.

Thanks for the help so far.

By the way: if your interested I found on the WEB an vacuum adjuster for four carbs at once. Simple design, few pennies for materials and works OK.
If you like i will send you the URL here OK??

Greetings Hans

zebedeus-bartolomeus Offline

Beiträge: 5

12.10.2009 19:42
#8 RE: my bike random does not start Thread geschlossen

Hello Art,

The video you send me has the correct view when the engine is running. The video shwos a bike on the road and it is running at about 3500 rpms according the sound i hear.

In this range the needles are acting the same way, no problem at all but......... it is when I open the throttle from idling up top ± 3500 rpms the the needles start irregular "bouncing".

Do you what to do when you start from scratch with a box full of parts and you rebuild your carbs with this?
I aligned and ajust them according the book and what is correct procedure to get the engine running.

I build the stuf together and mounted on the bike with the problem as result. Do I have the adjust the airmixture in this stage to or do I have to that first. Articles about this item are against eachother. One says no alignment, an other says how to align. It is so confusing probably because the book says that you are not allowed under no curcomstances to change the position of the airmixture screws

Unneccasery to say that the most of us did thatmostly by mistake.

Inbetween i found an other minor problem, it looks that my idle screw (the one behind and between the carbs) is not "long" enough to adjust the correct idling speed. I do not think that you can do anything wrong by reassembling the carbs set but on the otherhadn I was "smart "to swap two sparkplugcables.

Looking forward for any replies

Thanks for the help and hints sofar


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